JP2007071306A - Differential housing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce weight of a differential device provided with a differential gear and a differential housing as much as possible, suppress occurrence of noise and vibration, and to improve its durability. <P>SOLUTION: This differential housing 11 storing and supporting the differential gear is constituted by a plurality of structural bodies 12, 13 having different coefficients of linear expansion. The first structural body 12 arranged on the right side among them constitutes a so-called main body part of the differential housing 11 having an inside space storing substantially whole differential gear. An opening 14 for inserting the differential gear into the structural body 12 is formed on a left side face of the first structural body 12. The second structural body 13 on the other side is equivalent to a substantially disc-like lid attached and fixed to the structural body 12 to block the opening 14 of the first structural body 12, and its volume (volume of a constituent material) is smaller when compared with that of the first structural body 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a differential housing that houses and supports a differential gear.

  2. Description of the Related Art Conventionally, as a device including such a differential gear and a differential housing, for example, a device that allows differential of left and right drive wheels of an automobile as shown in Patent Document 1 is known. The differential gear includes a pinion gear coupled to the engine side and a ring gear meshing with the gear and coupled to the left and right drive wheels.

In addition, as seen in, for example, Patent Document 2, in recent years, the material of the differential housing has been changed from a conventional cast iron to a relatively light one such as aluminum or magnesium for the purpose of reducing the weight of such a device. Is underway.
Japanese Patent Laid-Open No. 2004-218749 JP-A-7-280069

However, such light non-ferrous metal materials such as aluminum-based materials and magnesium-based materials generally have a high coefficient of linear expansion and a large dimensional change with respect to a temperature change.
Therefore, when such materials are used, the positional relationship between the pinion gear and the ring gear of the differential gear is likely to change due to dimensional changes accompanying thermal changes, that is, thermal expansion and contraction, and the backlash of these gears is likely to change. Become. As a result, noise and vibration are likely to occur in the differential gear, and fluctuations in the power transmission state between the pinion gear and the ring gear are likely to occur.

  Further, the thermal expansion / contraction makes it easy for the distance between the bearings that support both ends of the ring gear to change, and the preload of the bearing tends to change. In this case, for example, when the distance between the bearings increases, the preload decreases, and noise and vibration are likely to occur in the bearings. On the other hand, when the distance is reduced, the preload increases and the seizure of the gear tends to occur. That is, as a result, the durability of the differential gear and the bearing tends to be lowered.

  The present invention has been made in view of such circumstances, and its object is to reduce the generation of noise and vibration while improving the durability while making the differential device including the differential gear and the differential housing as lightweight as possible. It is an object of the present invention to provide a differential housing.

In the following, means for achieving the above object and its effects are described.
The gist of the invention according to claim 1 is a differential housing that houses and supports a differential gear, and is composed of a plurality of structures having different linear expansion coefficients.

  According to this configuration, for example, as compared with a case where the structure of the differential housing has a high linear expansion coefficient, the thermal expansion and contraction of the differential housing is suppressed by the structure having a lower linear expansion coefficient. become. Therefore, the backlash increase / decrease of the ring gear constituting the differential gear and the pinion gear meshing with the ring gear can be suppressed, and the occurrence of noise and vibration and the increase of the rotational resistance of the differential gear can be suppressed, resulting in a decrease in durability of the gear. Will be suppressed. In addition, the increase or decrease in the preload of the bearing that supports the pinion gear or the ring gear is suppressed, and the decrease in the durability of the bearing can be suppressed.

  Further, according to this configuration, for example, the differential housing can be reduced in weight as compared with a case where the differential housing structure is entirely made of a low linear expansion coefficient.

  The “structure” here refers to a partition member such as a wall that partitions the differential gear housing space in the differential housing, and includes a connecting member such as a bolt and a seal member used to fix these. Not included.

  In addition, as an arrangement mode of such a structure, for example, according to the invention of claim 2, a ring gear support portion that supports a ring gear that constitutes the differential gear, a pinion gear support portion that supports a pinion gear meshing with the ring gear, and It is possible to adopt a structure in which the portion between the two is configured with a low linear expansion coefficient among the structures. In this case, for example, compared to the case where all of the portion between the ring gear support portion and the pinion gear support portion is configured with a structure having a high linear expansion coefficient, the thermal expansion and contraction of the portion is suppressed, so that the ring gear and Increase / decrease in the backlash of the pinion gear is preferably suppressed.

  According to a third aspect of the present invention, in the second aspect of the present invention, the structure having a low linear expansion coefficient is disposed from the ring gear support portion to the pinion gear support portion when viewed in the axial direction of the ring gear. This is the gist.

  According to this configuration, since the portion between the ring gear support portion and the pinion gear support portion is continuously a structure having a low linear expansion coefficient, for example, a structure having a low linear expansion coefficient is supported by the ring gear support portion and the pinion gear support. Compared with the case where the ring gear support portion and the pinion gear support portion are intermittently disposed between the ring gear support portion and the pinion gear support portion, the thermal expansion and contraction of the portion is more preferably suppressed. Therefore, increase / decrease in the backlash of the ring gear and the pinion gear can be more suitably suppressed.

  Further, as an arrangement mode of the structure, for example, according to the invention of claim 4, a portion between ring gear support portions that support the ring gear constituting the differential gear is defined as a linear expansion coefficient of the structure. It is possible to adopt such a configuration that is composed of a low one. In this case, for example, compared to the case where all the portions between the ring gear support portions are configured with a structure having a high linear expansion coefficient, the thermal expansion / contraction of the portion is suppressed, so that the bearing supporting the ring gear is reduced. Increase / decrease in the preload is suitably suppressed.

The gist of the invention according to claim 5 is that, in the invention according to any one of claims 2 to 4, the ring gear support portion is constituted by a structure having a low linear expansion coefficient.
According to this configuration, both the part between the ring gear support part and the pinion gear support part and the part between the ring gear support parts can be configured with a structure having a low linear expansion coefficient. Therefore, for example, the number of parts can be reduced as compared with the case where a structure having a low linear expansion coefficient is separately disposed in each of these portions.

  A sixth aspect of the present invention is the differential gear according to any one of the first to fifth aspects, wherein the differential gear includes a ring gear whose axis extends along the left-right direction, and the ring gear meshes with the ring gear. The gist is to have a pinion gear extending in the direction.

  Here, for example, in a mode in which the axis of the ring gear and the axis of the pinion gear are parallel, even if the ring gear and the pinion gear are relatively displaced in the direction of the axis due to the thermal expansion and contraction of the differential housing, the backlash of both gears increases or decreases. There is little to do. On the other hand, in the aspect in which the axial directions of the two gears are different as in the configuration of the sixth aspect, the backlash is easily increased or decreased along with the relative displacement of these gears in any direction. Therefore, in the configuration according to the sixth aspect, the operational effect obtained by the invention according to any one of the first to fifth aspects is particularly useful.

The gist of the invention of claim 7 is that, in the invention of claim 6, the axis of the ring gear and the axis of the pinion gear are offset in the vertical direction.
In such an aspect, the ring gear and the pinion gear are likely to be relatively displaced in the vertical direction due to the thermal expansion and contraction of the differential housing, for example, as compared with the aspect that is not offset as described above. Therefore, in the configuration according to the seventh aspect, the operational effect obtained by the invention according to any one of the first to fifth aspects is more useful.

The gist of the invention described in claim 8 is that, in the invention described in claim 6 or 7, the differential housing is composed of two structures divided in the left-right direction.
According to this configuration, the thermal expansion and contraction of the differential housing can be preferably suppressed particularly in the front-rear direction and the vertical direction.

  The invention according to claim 9 is the invention according to claim 8, wherein the two structures have different volumes, and these structures are formed of a material having a small linear expansion coefficient. The gist.

  According to this configuration, the thermal expansion and contraction of the differential housing can be suitably suppressed while suppressing an increase in weight due to the use of a material having a low linear expansion coefficient as much as possible.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 and 2 show an automobile rear differential device (final reduction gear) 10 having a differential housing 11 according to the present invention. FIG. 1 is a sectional view of the rear differential device 10 viewed from above, and FIG. It is the side view which looked at this from the left. In the following description, it is assumed that the upper side of FIG. 1 is the front side of the automobile and the rear differential device 10 and the lower side is the rear side. Further, the description will be made assuming that the left side of FIG.

  In the present embodiment, the housing of the rear differential device 10, that is, the differential housing 11, is configured as two structures 12 and 13 divided in the left-right direction. Of these, the first structure 12 arranged on the right side constitutes a main body portion of the differential housing 11 having an internal space for accommodating almost the entire differential gear. An opening 14 for inserting a differential gear into the structure 12 is formed on the left side surface of the first structure 12.

  The other second structure 13 corresponds to a substantially disk-shaped lid that is fixedly attached to the structure 12 so as to close the opening 14 of the first structure 12, and its volume (volume of the constituent material) is the first. The structure is smaller than the one structure 12. In the second structure 13, an annular peripheral edge 16 is fixed to a mounting surface 15 set on the left side surface of the first structure 12 by a plurality of bolts 17.

  The mounting surface 15 of the first structure 12 is formed to be the same plane over the entire circumference of the opening 14, and the surface of the peripheral edge portion 16 of the second structure 13 joined thereto is also the entire circumference. It is formed so that it may become the same plane similarly. The second structure 13 has a shape in which a portion closer to the center than the peripheral edge 16 bulges to the left of the peripheral edge 16.

  The front portion of the first structure 12 has a substantially cylindrical shape, and connecting portions 18 and 19 for fixing the device 10 to the chassis side of the automobile are provided on the outer peripheral side thereof. Similarly, the connecting portions 20 and 21 are provided in the rear portion of the first structure 12.

  An input shaft 24 to which rotational power from the engine side is transmitted is rotatably supported at the front portion of the first structure 12. The input shaft 24 is disposed so that the front end on the power input side protrudes from the differential housing 11, and a coupling member 25 connected to a propeller shaft (not shown) extending from the engine side is fixed to the front end. Has been. The outer peripheral side of the coupling member 25 is sealed with an annular seal member 32. Further, a pinion gear 26 constituting a differential gear is provided at the rear end of the input shaft 24 located in the first structure 12.

  The input shaft 24 is supported via a pair of tapered roller bearings 27 and 28. That is, the bearing mounting portions 29 and 30 into which the tapered roller bearings 27 and 28 are fitted in the first structure 12 constitute a pinion gear support portion that supports the pinion gear 26 in the differential housing 11. The axis of the input shaft 24, that is, the axis Lp of the pinion gear 26 extends along the front-rear direction of the apparatus 10.

  The front end surface of the inner race of the tapered roller bearing 27 on the front side of both the tapered roller bearings 27 and 28 is in contact with the rear end surface of the coupling member 25. Further, the rear end surface of the inner race of the tapered roller bearing 28 on the rear side is in contact with the front end surface of the base end portion of the pinion gear 26. In the present embodiment, the distance between the coupling member 25 and the pinion gear 26, that is, the inner races of the two bearings 27 and 28 are adjusted by adjusting the tightening degree of the nut 33 screwed into the male screw formed at the front end of the input shaft 24. The distance is adjusted. Thereby, the preload of both the bearings 27 and 28 is adjusted.

  The second structure 13 is provided so as to extend from the rear bearing mounting portion 30 of the first structure 12 to the connecting portion 20 at the rear end in the front-rear direction. The one structural body 12 is provided so as to extend over almost the whole from the upper end to the lower end.

  A ring gear 35 that is meshed with the pinion gear 26 and is driven to rotate by the gear 26 is accommodated in the rear half of the first structure 12. The ring gear 35 constitutes a differential gear together with the pinion gear 26.

  The ring gear 35 is bolted to the outer periphery of a differential case 36 that is rotatably supported in the differential housing 11. The ring gear 35 is disposed so that the axis Lr extends in the left-right direction (in this embodiment, the angle formed with the axis Lp of the pinion gear 26 is a right angle when viewed in the up-down direction).

  In the present embodiment, the pinion gear 26 and the ring gear 35 are hypoid gears, and the pinion gear 26 is offset so that its axis Lp is located below the axis Lr of the ring gear 35.

The left end of the differential case 36 is supported by the second structure 13 via a left tapered roller bearing 37, and the right end is supported by the first structure 12 via a right tapered roller bearing 38.
The left tapered roller bearing 37 is fitted in a left bearing mounting portion 40 set in the insertion hole 39 in the central portion of the second structure 13, and the outer race thereof is connected to the second structure 13 via an annular shim 45. It is in contact with the inner surface (right surface). The right tapered roller bearing 38 is fitted in a right bearing mounting portion 42 set in an insertion hole 41 formed in the right portion of the first structure 12, and the outer race has an annular shim 46 as described above. The first structure 12 is in contact with the inner surface (left surface).

  In these tapered roller bearings 37 and 38, the distance between both outer races is adjusted based on the thickness selection of the shims 45 and 46 when the apparatus 10 is assembled. That is, by selecting an appropriate thickness from a plurality of shims 45 and 46 having different thicknesses and adopting this when assembling the bearings 37 and 38 to the differential housing 11, the above adjustment can be achieved. Done.

Based on the adjustment of the distance between the outer races, the preloads of the bearings 37 and 38 are adjusted.
Further, the left and right positions of the ring gear 35 are adjusted based on the adjustment of the distance. By adjusting the left and right positions of the ring gear 35, the degree of tooth contact between the pinion gear 26 and the ring gear 35, that is, the size of the backlash is adjusted.

  The preload increases as the distance between the outer races in the bearings 37 and 38 is set shorter, and conversely, the preload decreases as the distance is set longer. Further, the backlash of the gears 26 and 35 increases as the left and right positions of the ring gear 35 are set to the left, and conversely, the backlash decreases as the left and right positions are set to the right.

  In the second structure 13, the left bearing mounting portion 40 to which the left tapered roller bearing 37 is fitted and the right bearing mounting portion 42 to which the right tapered roller bearing 38 is fitted in the first structure 12 are a differential housing. 11, a ring gear support portion that supports the ring gear 35 is configured.

  Drive shafts 51 and 52 that are rotatable about the axis Lr are inserted into the differential case 36 through cylindrical portions 36a and 36b that protrude from the left and right portions thereof. The drive shafts 51 and 52 are supported with the inner peripheral surfaces of the cylindrical portions 36a and 36b as sliding bearing surfaces. The outer peripheral sides of the drive shafts 51 and 52 are sealed with annular seal members 53 and 54.

  Driven gears 55 and 56 are fixed to the tips of the drive shafts 51 and 52 inside the differential case 36. A support shaft 57 is fixed to the differential case 36 so as to extend in a direction orthogonal to the axis Lr in the space between the driven gears 55 and 56, and two pinion gears 58 rotatably supported by the support shaft 57 are provided. The both driven gears 55 and 56 are engaged with each other.

  With this configuration, in the rear differential device 10, when rotational power from the engine is transmitted to the input shaft 24, the ring gear 35, that is, the differential case 36 is driven to rotate as the pinion gear 26 rotates. The rotation is transmitted to the gears 55, 56, and 58 via the support shaft 57, so that the drive shafts 51 and 52, and thus the driving wheels of the automobile are driven to rotate. Further, based on the rotation of each pinion gear 58 around the support shaft 57, the differential between both driven gears 55, 56, that is, both drive shafts 51, 52 is allowed.

  In the present embodiment, the constituent members of the differential gear, such as the input shaft 24, the ring gear 35, and the differential case 36, are formed of an iron-based material for the purpose of ensuring mechanical strength. Further, the bearings 27, 28, 37, and 38 are also formed of an iron-based material.

  On the other hand, the first structure 12 constituting the differential housing 11 is formed of an aluminum-based or magnesium-based material for the purpose of weight reduction or the like.

  By the way, lightweight non-ferrous metal materials such as aluminum-based materials and magnesium-based materials generally have a higher linear expansion coefficient than iron-based materials and the like, and have a large dimensional change with respect to temperature changes.

  Therefore, when such a material having a high linear expansion coefficient is used, the positional relationship between the pinion gear 26 of the differential gear and the ring gear 35 easily changes due to a dimensional change accompanying temperature change, that is, thermal expansion and contraction. The size of the backlash tends to change. As a result, noise and vibration are likely to be generated in the differential gear, and fluctuations in the power transmission state between the pinion gear 26 and the ring gear 35 are likely to occur.

  FIG. 3 shows experimentally obtained relationships between the temperature of the differential housing 11 and the backlash of the pinion gear 26 and the ring gear 35. Here, characteristics when the entire differential housing 11 is made of only an aluminum-based material, and characteristics when the entire differential housing 11 is made of only an iron-based material. Show.

  As can be seen from these characteristic lines, even when any material is used, the backlash tends to increase as the temperature rises. However, the amount of increase in backlash with respect to the same amount of temperature increase is greater when an aluminum-based material is used. That is, when a material having a relatively high linear expansion coefficient such as an aluminum material is used, the degree of change in the backlash due to thermal expansion and contraction increases.

  In addition, the thermal expansion / contraction causes the distance between the tapered roller bearings 37 and 38 that support the ring gear 35 at both ends thereof to easily change, and the preload of the bearings 37 and 38 easily changes. In this case, for example, when the distance between the bearings 37 and 38 increases, the preload decreases, and noise and vibration are likely to occur in the bearings 37 and 38. Conversely, if the distance is reduced, the preload increases and seizure of the gears 26 and 35 is likely to occur. That is, as a result, the durability of the differential gear and the bearings 37 and 38 tends to decrease.

  Therefore, in the present embodiment, unlike the first structure 12, the second structure 13 constituting the differential housing 11 is made of an iron-based material. As described above, since the iron-based material has a lower linear expansion coefficient than that of a lightweight non-ferrous metal material such as an aluminum-based material or a magnesium-based material, the thermal expansion / contraction of the first structure 12 is suppressed by the second structure 13. Become so. For example, the expansion deformation of the opening 14 due to the temperature rise is suppressed by the second structure 13, and as a result, the distance between the bearing mounting portion 30 constituting the pinion gear support portion and the left bearing mounting portion 40 constituting the ring gear support portion is reduced. The increase is suppressed and the backlash of the pinion gear 26 and the ring gear 35 is prevented from expanding.

  Here, for example, an iron-based material having a linear expansion coefficient of 10 to 14 × (10 to the sixth power) (unit: 1 / ° C.) is used as the “material having a low linear expansion coefficient”, and the linear expansion coefficient is 22 The above-mentioned lightweight non-ferrous metal material of ˜24 × (10 to the sixth power) (unit is 1 / ° C.) is used as “material with high linear expansion coefficient”.

In the present embodiment configured as described above, the following effects can be obtained.
(1) The differential housing 11 is composed of a plurality of (here, two) structures 12 and 13 having different linear expansion coefficients.

  By adopting such a configuration, for example, a structure having a lower linear expansion coefficient than the case where the structure of the differential housing 11 is entirely made of a material having a high linear expansion coefficient such as an aluminum-based material or a magnesium-based material. The body (here, the second structure 13 made of an iron-based material) suppresses the thermal expansion and contraction of the housing 11. Therefore, increase / decrease in the backlash of the pinion gear 26 and the ring gear 35 can be suppressed, generation of noise / vibration and increase in rotational resistance of the differential gear can be suppressed, and deterioration of the durability of the gear can be suppressed. Further, the increase and decrease in the preload of the tapered roller bearings 37 and 38 that support the ring gear 35 is suppressed, and the decrease in the durability of the bearings 37 and 38 is also suppressed.

  Further, according to the present embodiment, for example, the housing 11 can be reduced in weight as compared with the case where the structure of the differential housing 11 is entirely made of a ferrous material or the like having a low coefficient of linear expansion. Become.

  (2) In the present embodiment, the left bearing mounting portion 40 that is a ring gear support portion is set in the second structure 13. That is, the ring gear support portion is constituted by a structure having a low linear expansion coefficient.

  According to this, in the differential housing 11, the portion between the pinion gear support portion (bearing mounting portions 29, 30) and the ring gear support portion (left bearing mounting portion 40) and the ring gear support portions (bearing mounting portions 40, 42) are mutually connected. Both of the portions between the two can be formed of a structure (second structure 13) having a low linear expansion coefficient.

  More specifically, for example, the above-mentioned “portion between the pinion gear support portions (bearing mounting portions 29, 30) and the ring gear support portion (left bearing mounting portion 40)” is substantially the upper half of the second structure 13. Composed of parts. According to this, for example, compared with the case where all of the portion between the above-described pinion gear support portion and the ring gear support portion is configured by a structure having a high linear expansion coefficient such as an aluminum-based material or a magnesium-based material, the portion. Since the thermal expansion / shrinkage of the pinion gear 26 and the ring gear 35 is suppressed, the increase / decrease in the backlash of the pinion gear 26 and the ring gear 35 is preferably suppressed.

  On the other hand, as for the above-mentioned “portion between the ring gear support portions (bearing mounting portions 40, 42)”, the left side portion of the rear end portion of the differential housing 11 is constituted by the substantially lower half portion of the second structure 13. ing. According to this, for example, compared with the case where all of the portion between the ring gear support portions described above is formed of a structure having a high linear expansion coefficient such as an aluminum-based material or a magnesium-based material, the thermal expansion / shrinkage of the portion is performed. Therefore, the increase and decrease of the preload of the tapered roller bearings 37 and 38 that support the ring gear 35 are preferably suppressed.

  As described above, in the present embodiment, the above-mentioned “portion between the pinion gear support portion (bearing mounting portions 29, 30) and the ring gear support portion (left bearing mounting portion 40)” and “ring gear support portion (bearing mounting portion 40, 42) A common second structure 13 is disposed in both of the “parts between”. Therefore, for example, the number of parts can be reduced as compared with the case where a structure having a low linear expansion coefficient is separately disposed in each of these portions.

  (3) With the differential housing 11 viewed from the left side, that is, in the direction of the axis Lr, the second structure 13 is arranged from the pinion gear support portion (bearing mounting portion 30) to the ring gear support portion (left bearing mounting portion 40). Has been.

  According to this, a portion between the pinion gear support portion (bearing mounting portion 30) and the ring gear support portion (left bearing mounting portion 40) continuously becomes a structure (second structure 13) having a low linear expansion coefficient. . Therefore, for example, compared with the case where a structure having a low linear expansion coefficient is intermittently disposed between the pinion gear support portion and the ring gear support portion, the thermal expansion / shrinkage of the portion between the pinion gear support portion and the ring gear support portion Is more suitably suppressed. Therefore, the increase / decrease in the backlash of the pinion gear 26 and the ring gear 35 is more preferably suppressed.

  (4) The differential gear of the present embodiment includes a pinion gear 26 that rotates about the axis Lp extending along the front-rear direction, and a ring gear 35 that rotates about the axis Lr extending along the left-right direction. It will be.

  Here, for example, in a mode in which the axis of the pinion gear and the axis of the ring gear are parallel, even if the pinion gear and the ring gear are relatively displaced in the direction of the axis due to the thermal expansion and contraction of the differential housing, the backlash of both gears increases or decreases. There is little to do. On the other hand, in the aspect in which the axial directions of the two gears 26 and 35 are different as in the present embodiment, the backlash easily increases or decreases along with the relative displacement of the gears 26 and 35 in any direction. . Therefore, the effects (1) to (3) described above are particularly useful when the axial directions of the gears 26 and 35 are different as in the present embodiment.

(5) In the present embodiment, the axis Lp of the pinion gear 26 and the axis Lr of the ring gear 35 are offset in the vertical direction.
In such an aspect, the pinion gear 26 and the ring gear 35 are more likely to be relatively displaced in the vertical direction due to thermal expansion and contraction of the differential housing 11 as compared with, for example, an aspect that is not offset as described above. Therefore, in the embodiment in which the axis lines Lp and Lr of the both gears 26 and 35 are offset in the vertical direction as in this embodiment, the effects (1) to (3) described above are more useful. .

(6) The differential housing 11 of the present embodiment is composed of two structures (structures 12 and 13) divided in the left-right direction.
According to this, the thermal expansion and contraction of the differential housing 11 can be preferably suppressed particularly in the front-rear direction and the vertical direction.

(7) In the present embodiment, the second structure 13 having a small volume among the structures 12 and 13 is formed of an iron-based material having a low linear expansion coefficient.
According to this, the thermal expansion and contraction of the differential housing 11 can be suitably suppressed while suppressing an increase in weight as much as possible by using an iron-based material having a low linear expansion coefficient.

In addition, embodiment is not limited above, For example, it is good also as the following aspects.
In the above embodiment, in the state where the differential housing 11 is viewed from the left, that is, in the direction of the axis Lr, the second structure 13 is changed from the bearing mounting portion 30 which is the rear pinion gear supporting portion to the ring gear supporting portion (left bearing mounting portion). 40). Instead, as shown in FIGS. 4 and 5, for example, the second structure 13 extends from the bearing mounting portion 29, which is the front pinion gear support portion, to the ring gear support portion. You may extend 13 toward the front. According to this, compared with the said embodiment, since the front end of the 2nd structure 13 extends ahead, it becomes possible to suppress suitably the thermal expansion and contraction of the differential housing 11 to that extent. In particular, this can be suitably suppressed for the thermal expansion and contraction in the front-rear direction.

  In this embodiment, in the differential housing 11, the second structure 13 is disposed in a portion between the two tapered roller bearings 27 and 28 that support the pinion gear 26. That is, the part in the differential housing 11 is constituted by the second structure 13 having a low linear expansion coefficient. Therefore, increase / decrease in the distance between the outer races of both bearings 27, 28 due to the thermal expansion / contraction is suppressed, and as a result, increase / decrease in preload of both bearings 27, 28 is suppressed.

  In this embodiment, the second structure 13 is enlarged so that the second structure 13 covers almost the entire differential housing 11 when the differential housing 11 is viewed from the left, that is, in the direction of the axis Lr. ing. Along with this, the peripheral edge 16 of the second structure 13 that is in contact with the mounting surface 15 of the first structure 12 is also enlarged.

  In the above embodiment, the small structures of both structures 12 and 13 are formed of a material having a low coefficient of linear expansion, such as an iron-based material. It may be formed of a material having a low coefficient.

  In the above-described embodiment, the ring gear support is set in the second structure 13 that is a structure having a low linear expansion coefficient. In other words, the second structure 13 that is a structure having a low linear expansion coefficient is used as the ring gear support. Consists of. Instead of this, the ring gear support portion may be configured only with a structure with a high linear expansion coefficient, for example, by not providing a structure with a low linear expansion coefficient at the position where the ring gear support portion is set.

  In such a case, in the differential housing 11, for example, a structure having a low linear expansion coefficient is not provided in a portion between the left and right ring gear support portions that support the ring gear 35. You may make it comprise only with a body. Or you may make it provide a structure with a low linear expansion coefficient only in a part of part between the said left and right ring gear support parts. When a structure having a low coefficient of linear expansion is provided only in the part, one or two or more structures having a low coefficient of linear expansion are intermittently disposed in the part between the left and right ring gear support parts. Will be.

  Further, for example, in the differential housing 11, when viewed in the direction of the axis Lr, a structure having a low linear expansion coefficient may be provided only in a part of a portion between the pinion gear support portion and the ring gear support portion. Or you may comprise only the structure between these pinion gear support parts and ring gear support parts with a structure with a high linear expansion coefficient. In the case where a structure having a low linear expansion coefficient is provided only in a part of the portion between the pinion gear support portion and the ring gear support portion as described above, one or two or more structures having a low linear expansion coefficient are provided. The pinion gear support portion and the ring gear support portion are intermittently disposed at the portion between the pinion gear support portion and the ring gear support portion.

  In the above-described embodiment, the differential housing 11 has a two-part structure of the first structure 12 and the second structure 13, but the present invention is not limited to this, and may have a split structure of three or more parts. In this case, for example, structures having a low linear expansion coefficient made of an iron-based material or the like are disposed on the left and right sides of the differential housing 11, and an aluminum-based material, a magnesium-based material, or the like is formed between these two structures, that is, in the central portion. A structure having a high linear expansion coefficient may be provided.

  In the above embodiment, the differential housing 11 is composed of a plurality of structures divided in the left-right direction, but is not limited thereto, and may be composed of a plurality of structures divided in other directions.

  In this case, for example, as shown in FIG. 6, the differential housing 11 may be divided in the front-rear direction. In this example, the differential housing 11 is divided into two in the front-rear direction with a virtual plane including the axis Lr and extending in the up-down and left-right directions as a boundary. The first structure 12 located on the front side is a structure having a high linear expansion coefficient made of aluminum-based material or magnesium-based material, and the second structure 13 located on the rear side is made of iron-based material or the like. The structure is low. The attachment surface 15 of the first structure 12 is located on the virtual plane, and the peripheral edge portion 16 of the second structure 13 in contact with the first structure 12 extends annularly along the attachment surface 15. In this example, in the rear part of the differential housing 11, the part from one to the other of the left and right ring gear support parts that support the ring gear 35 is continuously constituted by a structure (second structure 13) having a low linear expansion coefficient. It will be. Therefore, for example, compared with an aspect in which a structure having a low linear expansion coefficient intermittently constitutes the portion, the increase / decrease in the distance between both ring gear support portions due to thermal expansion / contraction, and consequently the tapered roller bearings 37, 38 Increase / decrease in the preload is effectively suppressed.

  Further, for example, as shown in FIG. 7, the differential housing 11 may be divided in the vertical direction. In this example, most of the dividing boundary on the rear side of the differential housing 11 is set on a virtual plane including the axis Lr and extending in the front / rear / left / right direction, and the dividing boundary of the front side part includes the axis Lp It is set on a virtual plane extending in the left-right direction. The first structure 12 positioned on the upper side is a structure having a high linear expansion coefficient made of an aluminum-based material or a magnesium-based material, and the second structure 13 positioned on the lower side is linearly expanded made of an iron-based material or the like. It is a structure with a low coefficient. The mounting surface 15 of the first structure 12 is located on each of the virtual planes, and the peripheral edge 16 of the second structure 13 that abuts on the virtual plane extends annularly along the mounting surface 15. In this example, as described above, in the differential housing 11, a portion from one to the other of the left and right ring gear support portions that support the ring gear 35 is configured by a structure (second structure 13) that has a continuously low linear expansion coefficient. The Rukoto. Therefore, for example, compared with an aspect in which a structure having a low linear expansion coefficient intermittently constitutes the portion, the increase / decrease in the distance between both ring gear support portions due to thermal expansion / contraction, and consequently the tapered roller bearings 37, 38 Increase / decrease in the preload is effectively suppressed.

  In the above embodiment, the axis Lp of the pinion gear 26 is offset so as to be positioned below the axis Lr of the ring gear 35. However, the present invention is not limited to this, and the axis Lp may be offset so as to be positioned above the axis Lr. Good. Moreover, you may arrange | position both the gears 26 and 35 so that the axis line Lp and the axis line Lr may cross | interpose, without employ | adopting such an offset arrangement | positioning.

  The angle formed by the axis Lp of the pinion gear 26 and the axis Lr of the ring gear 35 does not necessarily have to be a right angle when viewed from above or below. For example, a spur gear or a helical gear may be used for the pinion gear and the ring gear, and these gears may be meshed so that the axes thereof are parallel to each other.

  In the above embodiment, the structure having a high linear expansion coefficient is made of an aluminum-based material or a magnesium-based material, and the structure having a low linear expansion coefficient is made of an iron-based material. However, the present invention is not limited to this. As long as the differential housing is configured by combining structures having different linear expansion coefficients, other materials may be adopted.

  In the above description, the present invention is applied to a rear-side differential device for driving a rear wheel of an automobile. However, the present invention is not limited thereto, and may be applied to a front-side differential device for driving a front wheel.

1 is a plan sectional view of a rear differential device for an automobile according to an embodiment. The side view of the state which looked at the rear differential apparatus for motor vehicles of the said embodiment from the left. The figure which shows the relationship between the temperature of a differential housing, and the backlash of a pinion gear and a ring gear. The plane sectional view of the rear differential device for cars of other examples. The side view of the state which looked at the rear differential apparatus for motor vehicles of the said other Example from the left. The side view of the state which looked at the rear differential apparatus for motor vehicles of the other Example different from the above from the left. The side view of the state which looked at the rear differential apparatus for motor vehicles of the other Example different from the above from the left.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Rear differential apparatus for motor vehicles, 11 ... Differential housing, 12 ... First structure, 13 ... Second structure, 24 ... Input shaft, 25 ... Coupling member, 26 ... Pinion gear, 27, 28 ... Pinion gear support Tapered roller bearings 29, 30 ... bearing mounting portion, 35 ... ring gear, 36 ... differential case, 37, 38 ... tapered roller bearing for supporting ring gear, 40 ... left side bearing mounting portion, 42 ... right side bearing mounting portion, 51, 52 ... Drive shaft, 55, 56 ... driven gear, 57 ... support shaft, 58 ... pinion gear, Lp ... pinion gear axis, Lr ... ring gear axis.

Claims (9)

A differential housing that houses and supports a differential gear,
A differential housing comprising a plurality of structures having different linear expansion coefficients. The differential housing according to claim 1,
The portion between the ring gear support portion that supports the ring gear that constitutes the differential gear and the pinion gear support portion that supports the pinion gear meshing with the ring gear is configured with a low linear expansion coefficient of the structure. Characteristic differential housing. The differential housing according to claim 2,
The differential housing, wherein the structure having a low linear expansion coefficient is disposed from the ring gear support portion to the pinion gear support portion when viewed in the axial direction of the ring gear. In the differential housing as described in any one of Claims 1-3,
A differential housing characterized in that a portion between ring gear support portions that support a ring gear that constitutes the differential gear is formed of the structure body having a low coefficient of linear expansion. In the differential housing as described in any one of Claims 2-4,
The differential gear housing is characterized in that the ring gear support portion is composed of a structure having a low linear expansion coefficient. In the differential housing as described in any one of Claims 1-5,
The differential gear has a ring gear whose axis extends in the left-right direction and a pinion gear that meshes with the ring gear and whose axis extends in the front-rear direction. The differential housing of claim 6, wherein
The differential housing, wherein the axis of the ring gear and the axis of the pinion gear are offset in the vertical direction. The differential housing according to claim 6 or 7,
The differential housing is composed of two structures divided in the left-right direction. The differential housing of claim 8,
The differential structure is characterized in that the two structures have different volumes, and the structures having a small volume are made of a material having a low linear expansion coefficient.

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